computer controlled distributor can't figure out why it won't spark.

the coil tested good between the BATT and TACH terminal but when I probe the BATT and the rotor button or the ground strap and rotor button all I get is a 1 on the ohm meter. I tried it on 3 different coils, one is brand new. I reused the rotor button because the new one didn't come with it. Is it possible for a rotor button to go bad?? I put the ohm meter on the one that looks like a horseshoe at 20k. I need some help.

 

Not sure I follow your description, but let me offer you a few things that might help....

First, you can't bench test ANYTHING on the secondary side of the igntion (the high voltage side). It has to handle much too much voltage to do any kind of bench test on it at low voltage or with an ohm meter. The fact that you have tried 3 different coils does prove the coil isn't the problem, however.

Rotor buttons don't go bad. They can wear out where they rub against the rotor tang, but they don't go electrically bad that I've ever encountered. The spark can get "shorted" on it's way to the plug wires by a bad cap or rotor, however, which allows the spark to find an "easier path to ground," which it will immediately take vs. doing it the hard way. And you may not find any visual signs of a problem, which is why replacement is the preferred method for those parts, not testing or visual inspection.

Last, for your coil to fire it needs 12V+ to the positive coil terminal AND IT NEEDS THE GROUND PATH ON THE NEGATIVE TERMINAL TO BE GROUNDED AND UNGROUNDED AT THE RIGHT TIME. That's the job of the pickup coil and the module. You can take the module out to have it tested but the pickup coil can't be removed without pulling the distributor.

However, you CAN do a quick test on the end result (what the coil is seeing). It requires a Dwell Meter. A dwell meter's readings are given in degrees (and there are setting for 4, 6 and 8 cylinder engines), but what that reading is REALLY telling you is a RATIO of open (ungrounded) time vs. closed (grounded) time. Some automotive volt/ohm meters also have a dwell meter setting. If yours does, you hook up the probes between the negative coil terminal and a good ground point. When cranking it should give you a reading OTHER THAN 0* or 45* (the top and bottom limits of the reading range when set for an 8 cylinder engine). A reading around 30* is typical for most 8 cylinder applications. But if it just sits there at 0* or 45* you know that either the pickup or the module isn't doing it's job grounding & ungrounding the negative side of the coil.

Not sure if that helps, but good luck with it!

 

the ignition wire that plugs into the BATT side off the distributor has 12 volts without cranking and 10 volts while cranking, is that the problem?

also I meant testing the BATT to the rotor button and the ground strap to the rotor button give me nothing on all 3 coils:
http://www.hotrodders.com/forum/test...ml#post1403624
3rd post down this explains it should be between 6000 to 30000, thats why I'm lost: